Just like social networking services on the Internet, the real world and the virtual world are getting integrated. Now, communications are made in center of SMS text messages and videos, but attempts to communicate various senses to make people at a remote place feel as if they were together with each other in more reality have been achieved. In particular, attempts to deliver the tactile sensation, which is a very important sense for people just like visual and auditory senses, to remote places and feel the sense thereat have been made.
To send a user a feeling as if the user touched a virtual object or send the user at a remote place the feeling when a robot or person touches the object, a lot of haptic apparatuses for sending a tactile sensation and a force feedback to hands and arms of people have been developed. Recently, as actuators have been more compact and the performance of computers has been improved, a lot of developments have been made, but still they cannot send enough senses. In addition, since such systems with a plenty of mechanical units are still big and heavy for general users, they are used by experts only in a special application field.
In particular, to deliver a tactile sensation of a fingertip, approaches have been suggested by using following methods: a method for using electro-active polymers which implements a tactile display by using the expansion of polymers by ion exchange and also has an advantage of implementing it flexibly, but mostly has small driving power or requires driving voltages of several kilovolts depending on materials; a method for using piezoelectric materials which may cause greater force, but makes a device be thick and difficult to be bent; a magnetic driving method which has less force, and makes a device be thick and difficult to be bent; a pneumatic method which may cause a force to be great and flexible but has a disadvantage of causing a system to be larger and more complicated because respective pneumatic lines must be connected to arrays to actuate them, etc. However, such methods have not been commercialized yet due to limitations on size, weight, performance of delivering senses, etc. Such apparatuses must be put on a hand, and this, particularly, makes the user feel uncomfortable and drops a sense of immersion when the information on the tactile sensation is transmitted with the visual information.
As one of the methods for overcoming such problems, Sony Corporation suggested a method for stimulating a neural cortex by using ultrasonic waves in the U.S. Pat. No. 6,536,440 B1 (granted on Mar. 25, 2003). But the conventional Patent technology merely suggests an apparatus for generating ultrasonic waves with a double structure to form a variety of patterns, and the possibility of delivering visual information as such an example.